As a standard for 3G mobile communication appears, a corresponding channel bandwidth is also increased to meet a requirement of communication. For example, in the 3G mobile communication, the channel bandwidth of a Wideband Code Division Multiple Access (W-CDMA) is 5 MHz, and the channel bandwidth of a Time Division-Synchronous Code Division Multiple Access (TD-SCDMA) is 1.6 MHz; however, for a standard for close to 4G mobile communication, for example, in a Long Term Evolution (LTE) system, the channel bandwidth is further increased to 20 MHz.
The increase of the channel bandwidth increases a frequency sweeping time inevitably. A traditional frequency sweeping process is to sweep each of all frequency points in a whole frequency band according to a frequency sweeping step length. The called frequency sweeping refers to that: Received Signal Strength Indication (RSSI) measurements are performed on each frequency point according to a frequency sweeping step length, and then RSSI values measured at all frequency points are sorted in an order of the RSSI values measured from largest to smallest and sent to a cell searching module to perform a cell search, so as to finish network registration and residence.
A frequency band may be swept through the above frequency sweeping process quite accurately and completely; however, as the frequency sweeping means that the RSSI measurement is performed on each frequency point of the whole frequency band and then the cell searching module performs the cell search on each frequency point according to the RSSI values in an order of the RSSI values from largest to smallest, larger consumption of time is caused. Even, a cell with a frequency point corresponding to a non-largest RSSI value is further searched in the frequency sweeping process, such that the cell fails to be searched successfully due to overtime.